Neurological complications in HIV infection are common and are significant sources of mortality and morbidity. The associated risk factors have not been clearly defined. Several studies have patients who are suited for analysis of peripheral neuropathy and can address the important clinical question of when a subject with asymptomatic neuropathy is most at risk for progressing to painful neuropathy. Some patients in this population with advanced HIV disease will likely have asymptomatic peripheral neuropathy at baseline, and will present an excellent opportunity for prospective study. Detailed quantitative assessments will be carried out to determine the incidence and course of peripheral neuropathy in this population. Risk factors for the development of new peripheral neuropathy, worsening of existing neuropathy, and progression to symptomatic peripheral neuropathy, such as CD4+ cell counts, HIV-1 viral load, and prior nucleoside analogue use, will be evaluated. The potential additive neurotoxic effects of hydroxyurea exposure in this population can also be analyzed.